Drilling bit



H. l. HENDERSON 2,894,727

DRILLING BIT July 14, 1959 Filed May 17, 1955 2 Sheets-Sheet 1 Homer f #ende/Jon IN V EN TOR.

July 14,v 1959 H. l. HENDERSON 2,894,727

DRILLING BIT Filed May 17, 1955 v 2 Sheets-Sheet 2 4 Homer f. Henderson f5 INVENTOR.

United States Patent DRILLING' BIT Homer I. Henderson, ASan Angelo, Tex. y Application May 17, '1955, Serial No. 508,837

6 Claims. (Cl. Z55-72) yMy invention 4relates in general to drilling bits and more particularly to drilling bits adapted for earth boring drills, and of the type generally known in this art lasa Roller Bit. v

An object of the invention is to provide a drill bit of the rolling cutter type wherein the life of the bearings of the bit rollers is materially increasedl due to the fact that the weight on the drill bit is supported by the drill bit-rolling cutters in contradistinction to conventional bits wherein the weight is supported by the rolling cutter bearings. In conventional drill bits the weight on the bit ris supported by the drill bit bearings, and' due tofthe magnitude of the Weight required to insure ecient drilling and due to the necessarily small bearings, necessitated by the small hole the useful life ofthe bit is norm'ally determined'bythe bearing life. 'Increased bit life results in a material saving in bit cost as well as a big saving in time lost going into and out of the hole with drill pipe to change bits.I l

Another object of the invention is the provision of a ringy type gear on the drill bit body to enmesh with the teeth of the bits rolling cutters. This ring type gear has the dual purpose of transmitting Weight to ythe bit rollers rotating the bit rollers. v Another object of the invention s the provision for rotating the drill pipe as a unit, 'at twice the rotational speed f the drill bit as a unit. This" provision results in straighter bore holes and less torque on the drill pipe.

' Another object of the invention is to provide for mounting a gear on the drill bitbody, said gear havinga tooth structure similar to the bits rolling cutter tooth structure and adapted to mesh with the teeth of the bits rolling cutter lto effectively cleanthe teeth ofthey bits rolling cutters and prevent accumulation of cuttingsbetween the ecient drill action.

Another object of the inventionV isto provide for disparate rolling cutters on the bit which provision results in the disparate rolling cutters.' tracking 'disparately which results in a different cutting pattern for ythe various rollingcutters forcing the teeth of subsequent rollers to cut olf the ridges left by the preceding rollers, which effects a big increase in bit eiiciency. j 7, Another object ofthe invention'i's the provision for mounting the rolling cutters insucha manner that va tapered shoulder is left at the bottom of the hole when cutting cores, said tapered shoulder acting to keep the bits rolling -cutter teeth. This. provision results in more bore hole straight and axial.

Another object of the invention is the provision of a c'am to break off drilled cores at a predetermined length sdthat-vthey do notbecome so long and heavy-as-to be ushed from the bore hole with difliculty.

Another object of the invention is the provision for mounting the rolling cutters in a carriage, which carriage is free to move axially with the drill pipe, between limits, whichprovision permits the dislodgingof particles which may become lodged between the rolling cutters and the drilling ring gear.

2,894,727 Patented July 14, 1959 ICC Other objects and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings, in which: v

Figure 1 shows a longitudinal cross-sectional view of the lower end of a drill pipe with the drill bit of this invention attached thereto, and positioned at the bottom of a bore hole, this particular embodiment being adapted for core drilling with so-called Reverse Circulation."

Figure 2 is a fragmentary cross-sectional view of the core breaker cam, said view taken along the line"2'-2, of Figure 1. y

Figure 3 is a detailed stretch out view showing the ring gear expanded and the relationship of the disparate rolling cutters.

Figure 4 is a detailed view showing one method'for. mounting the drill bit to the drill pipe, and one form of bearing for the mounting ring.

Figure 5 is a fragmentary cross-sectional view of the rolling cutter mounting struts taken along the line 5-5 of Figure l.

Figure 6 is a longitudinal sectional View of a modified form of my invention adapted for full hole drilling with circulation in the conventional sense.

Figure 7 is a fragmentary cross-sectional view showing the rolling cutter mounting struts and taken along the line 7-7 of Figure 6.

With reference to the drawing, the invention is'illus# trated as being incorporated with a drill pipe, and adapted to be rotated thereby.

Figure l shows an embodiment adapted to be used for core drilling in conjunction with Reverse Circulation. In this embodiment the drill pipe actually comprises two pipes, an outer pipe 10, and an inner pipe 11. The inner pipe is spaced from` the outer pipe by fins 12. The annulus between the pipes is designated 13. The arrows 14, indicate the direction of flow of the drilling uid. The outer annulus between the outer pipe 10 and the wall of the well bore B is normally iilled with drill iluid and/or packed o at the surface casing.

The drill bit body 15, is threaded at its upper end to engage threads on the lower end of Vthe drill pipe 10. The body has fluid passageways 16, to conduct drilling uid -to the rolling cutters 17. The lower end of the lbody 15, lhas a ring gear 18, to enmesh with the gear like teeth 19, of the rolling cutters 17. The packing ring 20, e'ects a seal between the inner drill pipe 11, and the drill body 15. Rotatably and slidably carried on the drill body 15, below the lower end of the outer pipe 10, is the annular mounting ring 21. To the mounting ring 21, are rigidly secured :by any conventional means a plurality of downwardly projecting struts 22. Each of the said struts 22, carries a rolling cutter 17. The rolling cutters are mounted on individual shafts 23,' by means of the low friction bearings 24, said bearings being designed to absorb the thrust and they may be packed with grease having low thermal coefficients and sealed in a conventional manner, by grease seals 45.' Thev lower ends of the struts 22, are bored to receive the ends of the shafts 23, for mounting the rolling cutters 17, to the struts 22.

The rolling cutters are frustiums of cones except that the inner frustrum face is not a plane, but a second cone 25, having cutting teeth 27, as shown by the dotted lines on the cones 17, of Figure 1. The taper of the cone 25, is such that the upper face will Ibe vertical when the rolling cutter is on a level bottom, as shown in a vertical hole by Figure 1. It will be seen that such a cutter will cut a core 26, that is cylindrical. During the process of cutting the core the bit will leave an enlarged tapered base 28, at the bottom of the hole as shown in Figure l; I have found that this enlarged tapered base is very elec- 3 tive in keeping the bit centered in the hole and results in the bit drilling straight and axially.

The mounting ring 21, is free to move axially between the bottom of the drill pipe 10, and the shoulder 29, on the drill body 15. This is enough movement to permit the drill bit teeth 19, to clear or disengage the teeth 18, on the bit body 15, to facilitate the occasional removal of cuttings or other debris, should they foul the bit. A cylinder 30, of material having a low coefficient of friction such as impregnated brass may be placed on the drill body as a bearing surface for the mounting ring 21. The ring 21 fits snugly about the bearing sleeve or cylinder 38 and is thereby held in substantial axial alignment, although it is free to rotate and to slide axially thereon within the limits described. Preferably, the ring and strut cutter carrier is formed as an integral assembly, `by weldin-g them together as shown.

Figure 2 shows a cross-sectional view of a core breaker cam 3l. This section is along line 2 2 of Figure l. This core breaker cam 3l, is secured to the inner drill pipe 11, such as by welding as shown in Figure l. This cam is necessitated for the reason that the drill bit would otherwise cut cores too long to be readily flushed from the hole and in such an eventually it would likely result in stoppage of the drill. As the drill bit drills deeper around the core 26, the core enters the pipe 11, and eventually the groove 32, shown dotted in Figure l of the cam 31, and it is deflected or forced off center by the cam, the displacement becoming greater and `greater as the bit drills deeper and deeper until the core finally breaks as shown `by the break 33, in Fgure 1.

Figure 3 is a diagrammatic stretched out view of the bottom ring gear portion 18, of the drill body 15, and showing the relationship of two disparate rolling cutters, 17a and 17h. The rolling cutter 17a, may have an even number of teeth such as twenty-four teeth, in which case the rolling cutter 17h, would have one tooth more or one tooth less, such as twenty-three teeth as shown. if one elects to have the pitch of the teeth, 18, 19a and 19h, all of the same pitch, then in this instance, the rolling cutter 17b, is slightly smaller than the rolling cutter 17a. It will be observed by referring to line tz-a, that when a single tooth on the rolling cutter 17a, is in full and direct mesh between any two teeth of the ring gear 18, then a tooth of the rolling cutter 17u is diametrically opposite. By referring to line b-b, it will be seen that when a tooth of the rolling cutter 17b, is in full and direct mesh between any two teeth of the ring gear 18, then a tooth is not diametrically opposite, but in contradistinction a tooth valley is diametrically opposite. lt will be seen that the rolling cutter 17h, will be forced to out with its teeth in opposite phase to the teeth of the rolling cutter 17a. Hence, the ridges or teeth 34, left in the rock 35, at the bottom of the hole `by the teeth of the rolling cutter 17a, will be cut at their center by the teeth of the rolling cutter 17h, and will eectively double the number of teeth in the rock 35, as shown by teeth 36. This results in a considerable increase in the efficiency of the bit of my invention over conventional bits.

This is due to the fact that in conventional bits the teeth of a subsequent rolling cutter, track exactly the teeth of the preceding rolling cutter and the weight or force, on the rolling critter teeth is largely absorbed by the teeth 34, in the rock 35, and there is little force on the digging points of the cutter teeth 19. In my invention by contradistinction, the weight, or force, on the rolling cutter bit is necessarily concentrated on the digging points of the teeth 19, and it effectively prevents the forming of large deep teeth 34, in the rock 35.

In Figure 3 l have shown the rolling cutter 17h as having teeth with the same pitch as the teeth 18, of the ring gear 15, and hence the cutter 17h, is somewhat smaller in diameter than the rolling cutter 17a; however I may use a modification wherein the cutter 17b is the same diameter as the cutter 17a, but having one tooth more, or one tooth less. When using this construction, the pitch of the teeth on the rolling cutter ll7b, do not exactly match the pitch of the teeth 18, but the resultant slippage does not entail excessive tooth wear, and does contribute some advantageous tangential shear on the teeth 34, of the rock 35. The preferred construction varies with the nature of the rock 35 which may be either; (l) cutters that a'r'e of equal pitch but disparate in diameter, or, (2) cutters that are equal in diameter but disparate in pitch, or, (3) a compromise between numbers' l and 2 above.

With the cutters 17 engaging the ring gear 18 on the bottom of the bit body 15, they constitute planetary gears and, therefore, inherently produce rotation of the ring and the strut assembly 21, 22 at one-half the rate of rotation of the drill pipe 10. This further rotation of the cutter assembly provides a reduction in torque on the drill pipe.

Figure 4 shows a modified mounting of the mounting ring 21. In this modification a ball bearing 38 (or this may be a roller bearing) is mounted between the ring 21, and the bit body 15. The ring 21, snugly tits the outer race of the bearing 38, but does have freedom of axial movement within limits. This bearing is normally packed with grease and two annular rings of resilient material, such as oil resistant rubber, are positioned above and below the ring 21, as shown by the rings 37, 37. The resilient rings 37, keep cuttings out of the bearing 38, but' by compression permit enough axial movement of the bit to disengage the teeth 19 and 18, should a stoppage develop. The upper and lower rings 37, are so designed that when the bit is in operating position, on the hole' bottom, the said rings are both in non-stressed condition. This requirement normally requires that the lower ring 37 be somewhat longer than the upper ring 37, the main' purpose of the upper ring 37, is to allow for upward ad-I justment as the teeth 18, and 19, wear, or are resharpened or cut.

Figure 5 is a fragmentary cross-sectional view taken on' line 5-5 of Figure 1. This view shows the section of the lower end of the bit body 15, just above the ring gear teeth. It will be noted that a plurality of segments 39, are

i removed from the ring gear to provide free passageways for the drill uid between the core 26, and the drill body 15. It will be understood that the teeth 18, extend completely across the lower face ofthe bit body 15, as originally made, and that segments of these teeth will of course be removed when the segments 39, are cut out to provide uid passageways. These segments may be cut with a broach or planer or by other cutting tools.

Figure 6 is an elevational, cross-sectional view showing an embodment of my invention adapted to full hole drilling when the direction of fluid circulation is in the conventional sense, as indicated by the arrows 14. In this modication the rolling cutters 17, cover most of the hole, leaving only a very small core 44, which core is subsequently washed into the mud apertures 43, and ground' into cuttings by the rolling cutters 17. In this modification the bit body 42, is threaded into the lowest collar 41, of the drill pipe 40. The lower portion of the bit body 42, has teeth 18, to effect a ring gear to enmesh with and drive the rolling cutters 17. Figure 6 shows the apertures 43, which are formed in the bit body 4Z, to permit passage of the drilling fluid and pieces of the core 44. These apertures may be formed by broaching, milling, drilling, ling, chiseling, torch burning, and/ or a combination of these arts, as well as any other metal removing method, or methods.

Figure 7 is -a cross-sectional view taken along line 7-7 of Figure 6. This view shows more clearly the apertures 43, in the drill body ring gear, said apertures being pro-- vided to permit ow of the drilling fluid.

seam/a7 Even though it has been stated that the drill bit of Figure 6 has been adapted for conventional circulation', it Will be obvious to those skilled in the art that either bit might be used with the alternate circulation. If desired, the drill bit of Figure 1 could have full length rolling cutter cones to cut substantially a full hole, leaving only a fragile very thin core. Similarly the drill bit of Figure 6, could be provided with much shorter rolling cutter cones so that the core 44, is as large as desired, within limits, and in which case the core 44, would be retrieved with a conventional wire line core barrel or retrieved upon the removal of the drill pipe.

Although the invention has been described in its` preferred forms with a certain degree of particularity, it is understood that the present disclosures of the preferred forms have been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

I claim as my invention:

1. A. drill bit comprising a body adapted to be secured to the lower end of a string of drill pipe and rotated thereby, a ring gear on the lower end of said body, a cutter carrier on said body, said cutter carrier and said ring gear being capable of relative rotation, and at least two toothed cutters rotatably supported on said cutter carrier below said ring gear `and `in simultaneous mesh therewith, the teeth of each of said cutters being of uniform pitch around the circumference thereof, one of said cutters having more teeth than the other of said cutters.

2. A drill bit comprising a body adapted to be secured on the lower end of a string of drill pipe and rotated thereby, a ring gear fixed -on the lower end of said body, a cutter carrier rotatably mounted on said body, at least two toothed cutters rotatably supported on said carrier below said ring gear and in mesh therewith, one of said cutters having more teeth than the other of said cutters, the teeth of both of said cutters being of regular pitch and being simultaneously in mesh with the teeth on said ring gear.

3. A drill bit as delined in claim 2 wherein said other cutter is of greater pitch than said one cutter.

4. A drill bit as defined in claim 3 wherein said one cutter is of greater diameter than said other cutter.

5. A drill bit comprising a body adapted to be secured on the lower end of a string of drill pipe so as to be rotated thereby, at least two toothed cutters rotatably supported on said body, the teeth of each of said cutters being of uniform pitch around the circumference thereof, one of said cutters having more teeth than the other of said cutters, and common gear means in mesh with the teeth of said cutters simultaneously to restrict relative rotation thereof to the same tooth by tooth rate of rotation.

6. A drill bit comprising a bit body adapted to be secured onto the lower end of a drill pipe so as to be rotated thereby, a pair of toothed cutters rotatably supported on said body, common 'gear means on said body having teeth thereon in continuous mesh simultaneously with said pair of toothed cutters, said gear means and said toothed cutters being rotatable relative to each other, the teeth of. one of said cutters being of dierent pitch than the teeth of the other of said cutters.

References Cited in the le of this patent UNITED STATES PATENTS 1,306,674 Esseling lune 10, 1919 1,828,165 Abegg Oct. 20, 1931 1,874,070 Wellensiek Aug. 30, 1932 1,896,251 Scott Feb. 7, 1933 1,940,996 Carr Dec. 26, 1933 2,634,106 Foster Apr. 7, 1953 2,639,896 Francis May 26, 1953 

